1. Field of the Invention
This invention relates to air filters. In particular, this invention relates to air filters incorporating filtering media and a centrifugal fan, the centrifugal fan preferably being attachable to the rotor plate of a common ceiling fan. The invention also relates to an industrial embodiment attachable to a rotary motor.
2. Description of the Related Art
Air in homes or in business workplaces typically includes a colloid suspension of smoke particles, plant pollens, mold spores, and dust particles. Pollen and mold spores suspended in the air of a home or a workplace are common allergens which may cause sinusitis or hay fever, and other respiratory ailments. Dust suspended in the air may be harmful to persons in a home or workplace who have emphysema or asthma. Additionally, airborne smoke and dust tends to discolor and soil items in a home or workplace such as curtains and furniture. In the workplace, the dangers of pollutants in the indoor environment are oftentimes more harmful. For instance, the fumes emitted from cleaning solvents, hydrocarbons, acids and paint may cause serious long term health risks. Thus, it is widely seen as desirable to create home and workplace environments whose air is substantially free of airborne smoke, pollen, mold spores, dust and other harmful pollutants.
Several types of apparatus for cleaning and filtering air within a home or workplace are known. Many have disadvantages. For example, free standing electric air cleaning machines, typically incorporating an air impeller and a filtering medium mounted in the path of air flow, take up useable space within a room and typically create undesirable background noise. Another air filtering device having disadvantages is a carbon filter or an electrostatic air filter which is installable as an auxiliary element of a building""s central air and heating system. Such systems are mechanically complex, and are expensive to construct, maintain, and operate.
The instant inventive air filtering device overcomes such disadvantages, among others, by providing a mechanically simple air filter which is economical to construct and operate, which takes up virtually no living or working space of a home or workplace, and which creates virtually no background noise. Such benefits are obtained through the provision of a centrifugal fan having a filtering media attached thereto and disposed therearound, the centrifugal fan and filtering media assembly being attachable to and rotatable by the rotor plate of a common ceiling fan, such ceiling fan having its fan blades removed. In another embodiment, the air filtering media is disposed at the periphery of a plate. The filtering media is secured in a compartment defined between the plate and a cover. Additionally, a larger, industrial embodiment may be attached to and rotatable by a more powerful rotary motor.
3. Prior Art Patents
U.S. Pat. No. 4,849,862 issued Jul. 18, 1989, to Diskin, et al., discloses a ceiling suspended air purifying light fixture.
U.S. Pat. No. 4,750,863 issued Jun. 14, 1988, to Scoggins discloses a fan shroud filter.
U.S. Pat. No. 4,450,756 issued May 29, 1984, to Kling discloses a fume exhaust device.
U.S. Pat. No. 4,840,650 issued Jun. 20, 1989, to Matherne discloses a ceiling fan filter.
U.S. Pat. No. 4,422,824 issued Jun. 27, 1983, to Eisenhardt discloses a germ killing ceiling fan.
U.S. Pat. No. 4,790,863 issued Dec. 13, 1988, to Nobiraki discloses an air cleaner incorporating a centrifugal fan.
U.S. Pat. No. 5443,625 issued Aug. 22, 1995, to Schaffhausen discloses an air filtering fixture.
U.S. Pat. No. 4,676,721 issued Jun. 30, 1987, to Hardee discloses a ceiling fan air cleaner.
None of the above disclosed patents disclose, teach or describe the novel, inventive, useful and unique characteristics and features of the present inventive air filtering device.
The present inventive air filtering device comprises an upper circular plate, preferably between three and four feet in diameter, the circular plate being adapted for fixed attachment to and rotation by the rotor plate of a common ceiling fan; such ceiling fan having its blades removed.
Upon removal of the fan blades of, for example, a common four bladed ceiling fan, screw receiving fan blade attachment apertures of the ceiling fan""s rotor plate are exposed. Typically, the lower surface of such rotor plate is elevated above the lower surface of the ceiling fan""s motor housing. The upper circular plate of the present inventive air filtering device preferably extends conically upward, such upward extension terminating in a flattened circular upper end which is fitted for attachment to the rotor plate of the ceiling fan. Screw receiving filter attachment apertures are either drilled into or molded into the flattened upper end of the circular plate, such apertures being positioned and aligned so that they may underlie the fan blade attachment apertures of the ceiling fan""s rotor plate. Also, a light fixture shaft aperture may be drilled or molded into such flattened open end. Such configuration of the upper circular plate and the filtering attachment apertures allows the air filtering device to be easily and conveniently attached to the rotor plate by means of screws or bolts.
A multiplicity of fan blades are fixedly attached to or molded as a part of the lower surface of the circular plate so that they extend downwardly therefrom; the fan blades being radially configured and aligned in conformity with the common configuration of the blades of a centrifugal fan or pump. Upon operation of the ceiling fan motor to rotate the upper circular plate along with the blades extending therefrom, the blades centrifugally accelerate air outwardly in all radial directions.
Lower structural support of the blades is preferably provided by an annular ring which is molded as a part of or fixedly attached to the lower outside corners of the blades. Preferably, the annular ring presents an outwardly facing peripheral surface extending annularly around the outer edges of the fan blades. The outwardly facing peripheral surface preferably has a snap ridge receiving channel extending annularly therearound; the snap ridge receiving channel serving the function of securely and interchangeably holding a cylindrical air filter retaining frame containing an air filtering medium.
The air filter retaining frame preferably comprises a plastic downwardly opening U-channel ring, and a plastic upwardly opening U-channel ring, the U-channel rings preferably being interconnected by a pair of concentric cylindrical wire mesh walls. Preferably, the upper and lower edges of the wire mesh walls are respectively embedded within and held by the lower and upper surfaces of the U-channel rings. The combination of the upper and lower U-channel rings, and the concentric wire mesh walls define a cylindrical filtering medium retaining and supporting space. Within such space, any of several air filtering media may be deposited. Suitable air filtering media which may be deposited within such cylindrical space are activated charcoal, a pleated fiberglass mesh, pleated woven fabric filters either chemically treated or impregnated with activated charcoal, high efficiency particle arresting (HEPA) filters, or continuations of such filtering media.
A snap ridge is preferably molded as a part of the lower U-channel ring so that the snap ridge extends inwardly from such ring""s inwardly facing surface. Preferably, the filter retaining frame is closely fitted to the fan blades so that it may be slidably mounted over the outer edges of the fan blades, and so that it may be manually pressed into place, causing the snap ridge to snap into place within the snap ridge receiving channel of the annular ring. Removal and replacement of the air filter retaining frame is conveniently accomplished by manually pulling the air filter retaining frame downwardly, away from the blades, causing such frame to slide away from the fan blades. An opposite upward sliding motion imposed upon a new air filtering frame containing a fresh air filter medium replaces the removed air filter retaining frame.
In operation, upon rotation of the assembled air filtering device by the motor of a ceiling fan, air is drawn upward into the interior space of the air filtering device, and the air is centrifugally accelerated outward in all radial directions by the fan blades. The air then flows through the air filter retaining frame and through the air filtering medium contained therein. Such flow of air accomplished continuous and noiseless filtration of the air, and accomplishes desirable air circulation.
In the alternative embodiments of the air filtering device, the air filtering media is held between an upper plate coupled with the rotary motor and a cover. The filtering media compartment or compartments are further defined by the fan blades forcing air through the media and removable doors on the outside of the media near the periphery of the device. In one alternative embodiment, the doors are slidably received within slits positioned around the periphery of the plate. In the other embodiment, the doors are pivotably connected to the device at spacers securing the cover to the plate. Furthermnore, in the alternative embodiments, the blades are progressively curved so that the angle of the blades is more tangential at the inner edge than the outer edge of each blade.
Accordingly, it is an object of the present invention to provide an air filtering device which is readily installable upon the rotor plate of a common ceiling fan; such ceiling fan having its fan blades removed.
It is a further object of the present invention to provide such an air filtering device which utilizes centrifugal fan blades for accelerating the air.
It is a further object of the present invention to provide such an air filtering device further having an air filter retaining frame containing an air filtering medium, such frame being annularly mounted around the outer periphery of the centrifugal fan blades.
It is a further object of the present invention to provide such an air filtering device further providing a snap ridge and a snap ridge receiving channel for easy installation, removal, and replacement of the air filter retaining frame.
It is a further object of the present invention to provide such an air filtering device which is economically constructed, and which is quiet in operation.
It is a further object of the invention to provide an air filtering device having filtering media compartments between the upper plate and lower cover that remove particulates from the air.
It is a further object of the present invention to provide an air filtering device with doors covering the air filtering media that are easy to open and secure to replace the filtering media.
A still further object of the present invention is to provide an air filtering device that moves a large quantity of air and has great durability for filtering air laden with destructive properties in industrial environments.
A further object of the invention is to provide an air filtering device that forces air through the filtering media at high enough velocity to use a variety of types of filtering media.
Another object of the present invention is to provide an air filtering device having a plurality of centrifugal fan blades shaped to pull air axially towards the device and through the filtering media.